Transmission system.



O. T. LADEMAN.

TRANSMISSION SYSTEM.

APPLICATION rum) FEB. 15, 1909.

Patented Feb. 15, 1910.

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5 7M 4 m W6 M fl $6 UNITED STATES PATENT OFFICE.

OTTO LADEIVIAN, OF MILWAUKEE. WISCONSIN, ASSIGNOR TO RAILIVAY TELE-PHONE & ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OFILLINOIS.

TRANSMISSION SYSTEM.

Specification of Letters Patent.

Application filed February 15, 1909.

l.atented Feb. 15, 1910.

Serial No. 478,071.

To all whom it may concern:

Be it known that I, O'r'ro T. LADEMAN, citizen of the United States,residing at Milwaukee, in the county of Milwaukee and State ofWisconsin, have invented a certain new and useful Improvement inTransmission Systems, of which the following is a full, clear, concise,and exact description, reference being had to the accompanying drawings,forming a part of this specification.

My invention relates to telephone transmission systems, and has for itsobject the provision of an improved long distance transmission systemespecially applicable for use in railway service.

The general object of my invention is to so arrange the variousinstrumentalities at the various stations as to properly equalize thetalking currents which are sent out from the central or transmittingstation.

More specifically, my invention contemplates the use of telephonereceivers of different effective resistances to the voice currents,depending upon the distance of these receivers from the transmittingstation, so that not only will the currents be properly distributed andeach receiving circuit be apportioned its proper share of current, butall the available current which is allotted to each receiving branchwill be available for proper use in the receiving element itself.

Further details and advantages of my invention will be apparent from theconstruction, which I will now describe in connection with theaccompanying drawing, illustrating one embodiment thereof, in which Ihave shown a central station A, and substations B, C, D, E and F.

The transmission circuit comprises line conductors 1 and 2, which unitethe various stations, and it is contemplated that this transmissionsystem is adapted for use along railways where the transmissionconductors 1 and 2 are of relatively high resistance compared to theordinary talking circuits met with in the operation of telephonetransmis sion. I have shown at each station a transmitter 3, a battery4, the primary 5 of an induction coil, and the secondary 6 of aninduction coil. The local transmitting circuit is closed by means of akey 7, which is depressed when the operator at either station desires totalk into the transmitter 3 associated with that station. I also show acondenser S in each bridge circuit, which aids in preventing thedeflection of telegraph currents through the telephone circuits. Eachstation is likewise provided with one of my improved receivers 9, whichreceiver is in series with the secondary coil (5, and the condenser 8. Ibridge an adj ustable impedance or resistance coil 10 around thereceivers 9, through the interposition of the spring 11, which isadapted for closing this shunt circuit when key 7 is operated. When thekey 7 is operated, and the ope ator talks into the transmitter 3 at saidstation, the local talking circuit is closed, and an adjustableimpedance is bridged around the receiver to avoid the necessity of thetalking current passing in series through the high resistance receiver.

The receivers 9, as stated, are provided with coils 12, 12, which coilsserve to actuate the diaphragm 13, to transmit the currents into soundwaves. These coils 12 at the various receivers are of ditl'cringcllcctive resistances to the voice currents traversing the variousbridges. For instance, station A has been taken as the transmittingstation, which is occupied by the train despatcher, and it is necessarythat when he is talking into his receiver, all of the stations B, U, D,E, and I can properly hear him. For this reason, the receiver 9, at thestation B, is of very much higher resistance than the receiver 9 atstation I 1 lind, in practice, that I do not necessarily have to varythe resistances of all the receivers, as I can take a group of receiversnearest the t 'ansmitting station, and allot them a certain resistance,and take the next group and allot them a less resistance, and so onalong the line. I also (ind, in practice, that I get good results itwires of ditlercnt specific resistances are used to elt'ect this result.I can thus make the resistance of these receivers adjustable, as shownat station A, where terminals of the coils are brought out to contactpoints, and a shunt wire 14 may be used to short circuit various turns,if desired.

Having thus described the preferred em bodiment of my invention, what Iclaim as new and desire to secure by Letters Patent of the United Statesis:

1. A telephone transmission system comprising a telephone circuitconnecting a central station with a plurality of substations, atelephone set at the central station, and a telephone set at eachsub-station, the receivers of the various sub-station sets having lowerimpedances as their distance from the central station increases.

2. A telephone transmission system comprising a telephone circuitconnecting a' central station with a plurality of sub-stations, a localtelephone set at the central station, and a telephone set at eachsubstation, the receivers of the various substations oiiering lowereffective resistance to the flow of the voice currents emanating fromthe central station, the farther these said receivers are away from saidcentral station, thereby to more evenly distribute the central stationvoice currents through the sub-station telephones.

8. A telephone transmission system comprising a telephone circuitconnecting a central station with a plurality of sub-stations, a localtelephone set at the central station, and a telephone set at eachsubstation, the windings of the receivers of the various sub-stationsoiiering lower effective resistance to the flow of the voice currentsemanating from the central station, the farther these receivers are awayfrom said central station, thereby to more evenly distribute the centralstation voice currents through the sub-station telephones.

4. A telephone transmission system com prising a telephone circuitconnecting a cent al station with a plurality oi sub-stations, atelephone set at the central station, a telephone set at eachsub-station, the receivers of the various sub-station sets having lowerimpedances as their distance from the central station increases, andswitching means for establishing a shunt circuit around said receivers.

5. A telephone transmission system comprising a telephone circuitconnecting a central station with a plurality of sub-stations, a localtelephone set at the central station, a telephone set at eachsub-station, the receivers of the various sub-stations otlering lowerettective resistance to the flow of the voice currents emanating fromthe central station, the farther these said receivers are away from saidcentral station, thereby to more evenly distribute the central stationvoice currents through the sub-station telephones, and switching meansfor establishing, a shunt circuit around said receivers.

6. A telephone transmission system comprising a telephone circuitconnecting a central. station with a plurality of sub-stations, a localtelephone set at the central station, a telephone set at eachsub-station, the windings of the receivers of the various substationsoffering lower effective resistance to the flow of the voice currentsemanating from the central station, the farther these said receivers areaway from said central station, thereby to more evenly distribute thecentral station voice currents through the sub-station telephones, andswitching means for establishing a shunt circuit around said receivers.

7. A telephone transmission system comprising a telephone circuitconnecting a central station with a plurality of sub-stations, a localtelephone set at the central station, a telephone set at eachsub-station, the Windings of the receivers of the various sub-stationsoffering lower effective resistance to the How of the voice currentsemanating from the central station, the farther these said receivers areaway from said central station, thereby to more evenly distribute thecentral station voice currents through the sub-station telephones, andswitching means for establishing an adjustable shunt circuit around saidreceivers.

8. A telephone transmission system com prising a. telephone circuitconnecting a central station with a plurality of sub-stations, a localtelephone set at the central station, a telephone set at eachsub-station, the windings of the receivers of the various sub-stationsoffering lower effective resistance to the flow of the voice currentsemanating from the central station, the farther these said receivers areaway from said central station, thereby to more evenly distribute thecentral station voice currents through the sub-station telephones, andswitching means for establishing a shunt circuit of adjustable impedancearound said receivers.

9. A telephone transmission system com- )risin a hi 'h resistance teleshone circuit OTTO T. LADEMAN.

lVitnesses MAX LABEL, O. M. VIENNIEL.

